Effect of nucleation on icy pebble growth in protoplanetary discs

Katrin Ros; Anders Johansen; Ilona Riipinen; Daniel Schlesinger
2019 | Astron Astrophys | 629 (A65)

Solid particles in protoplanetary discs can grow by direct vapour deposition outside of ice lines. The presence of microscopic silicate particles may nevertheless hinder growth into large pebbles, since the available vapour is deposited predominantly on the small grains that dominate the total surface area. Experiments on heterogeneous ice nucleation, performed to understand ice clouds in the Martian atmosphere, show that the formation of a new ice layer on a silicate surface requires a substantially higher water vapour pressure than the deposition of water vapour on an existing ice surface. In this paper, we investigate how the difference in partial vapour pressure needed for deposition of vapour on water ice versus heterogeneous ice nucleation on silicate grains influences particle growth close to the water ice line. We developed and tested a dynamical 1D deposition and sublimation model, where we include radial drift, sedimentation, and diffusion in a turbulent protoplanetary disc. We find that vapour is deposited predominantly on already ice-covered particles, since the vapour pressure exterior of the ice line is too low for heterogeneous nucleation on bare silicate grains. Icy particles can thus grow to centimetre-sized pebbles in a narrow region around the ice line, whereas silicate particles stay dust-sized and diffuse out over the disc. The inhibition of heterogeneous ice nucleation results in a preferential region for growth into planetesimals close to the ice line where we find large icy pebbles. The suppression of heterogeneous ice nucleation on silicate grains may also be the mechanism behind some of the observed dark rings around ice lines in protoplanetary discs, as the presence of large ice pebbles outside ice lines leads to a decrease in the opacity there.

Interactions between the atmosphere, cryosphere and ecosystems at northern high latitudes

Michael Boy; Erik S. Thomson; Juan-C. Acosta Navarro; Olafur Amalds; Ekaterina Batchvarova; Jaana K. Bäck; Frank Berninger; Merete Bilde; Pavla Dagsson Waldhuserova; Dimistri Castaréde; Maryam Dalirian; Gerrit de Leeuw; Monika Wittman; Ella-Maria Duplissy (nèe Kyrö); J. Duplissy; A. M. L. Ekman; Keyan Fang; Jean-Charlet Gallet; Marianne Glasius; Sven-Erik Gryning; Henrik Grythe; Hans-Christen Hansson; Margareta Hansson; Elisabeth Isaksson; Trond Iverson; Ingibjörg Jónsdottir; Ville Kasurinen; Alf Kirkevåg; Atte Korhola; Radovan Krejci; Jon Egill Kristjansson; Hanna K. Lappalainen; Antti Lauri; Matti Leppäranta; Heikki Livhvainen: Risto Makkonon; Andreas Massling; Outi Meinander; E Douglas Nilsson; Haraldur Ólofsson; Jan B. C. Pettersson; Nonne L. Prisle; Ilona Riipinen; Pontus Roldin; Meri Ruppel; Matt Edward Salter; Maria Sand; Ovind Seland; Heikki Seppä; Henrik Skov; Joanna Soares; Andreas Stohl; Johan Ström; Jonas Svensson; Erik Swietlicki; Ksenia Tabakova; Thorstur Torsteinsson; Aki Virkula; Gesa A. Weyhenmeyer; Yusheng Wu; Paul Zieger; Markku Kulmala
2019 | Atmos. Chem. Phys. | 19 (2015-2061)

The Nordic Centre of Excellence CRAICC (Cryosphere–Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols.

The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change–cryosphere interactions that affect Arctic amplification.

Cloud droplet activation of black carbon particles with organic compounds of varying solubility

Dalirian, M.; Ylisirnio, A.; Buchholz, A.; Schlesinger, D.; Strom, J.; Virtanen, A.; Riipinen, I.
2018 | Atmos. Chem. Phys. | 18 (12477-12489)

Impacts of future European emission reductions on aerosol particle number concentrations accounting for effects of ammonia, amines and organic species

Julin, J.; Murphy, B. N.; Patoulias, D.; Fountoukis, C.; Olenius, T.; Pandis, S. N.; Riipinen, I.
2018 | Environ. Sci. Technol. | 52 (692-700)

Robust metric for quantifying the importance of stochastic effects on nanoparticle growth

Olenius, T.; Pichelstorfer, L.; Stolzenburg, D.; Winkler, P. M.; Lehtinen, K. E. J.; Riipinen, I.
2018 | Sci Rep | 8

Exploring the potential of nano-Köhler theory to describe the growth of atmospheric molecular clusters by organic vapors using cluster kinetics simulations

Kontkanen, J.; Olenius, T.; Kulmala, M.; Riipinen, I.
2018 | Atmos. Chem. Phys. | 18 (13733-13754)

New particle formation and growth: Creating a new atmospheric phase interface

Olenius, T.; Yli-Juuti, T.; Elm, J.; Kontkanen, J.; Riipinen, I.
2018 | Elsevier Science Publishers | Physical Chemistry of Gas-Liquid Interfaces (315-352) | ISBN: 9780128136416

How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

Bourgeois, Q; Ekman, AML; Renard, JB; Krejci, R; Devasthale, A; Bender, FAM; Riipinen, I; Berthet, G; Tackett, JL
2018 | Atmos. Chem. Phys. | 18 (10) (7709-7720)
aerocom phase-ii , air pollution , caliop , calipso , cloud , models , ocean , satellite-observations , transport , vertical-distribution
The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a 9-year period (2007-2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained in Aire sur l'Adour (France) using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT - and thus potentially located above low-level clouds - is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for processes determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

Effect of bisulfate, ammonia, and ammonium on the clustering of organic acids and sulfuric acid

Myllys, N.; Olenius, T.; Kurtén, T.; Vehkamäki, H.; Riipinen, I.; Elm, J.;
2017 | J Phys Chem A | 121 (4812-4824)

New particle formation from sulfuric acid and amines: Comparison of monomethylamine, dimethylamine, and trimethylamine

Olenius, T.; Halonen, R.; Kurtén, T.; Henschel, H.; Kupiainen-Määttä, O.; Ortega, I. K.; Jen, C. N.; Vehkamäki, H.; Riipinen, I.;
2017 | J. Geophys. Res.-Atmos. | 122 (7103-7118)

Revising the hygroscopicity of inorganic sea salt particles

Zieger, P.; Väisänen, O.; Corbin, J.; Partridge, D. G.; Bastelberger, S.; Mousavi-Fard, M.; Rosati, B.; Gysel, M.; Krieger, U.; Leck, C.; Nenes, A.; Riipinen, I.; Virtanen, A.; Salter, M.
2017 | Nat. Commun. | 8 (15883)

Sea spray is one of the largest natural aerosol sources and plays an important role in the Earth’s radiative budget. These particles are inherently hygroscopic, that is, they take-up moisture from the air, which affects the extent to which they interact with solar radiation. We demonstrate that the hygroscopic growth of inorganic sea salt is 8–15% lower than pure sodium chloride, most likely due to the presence of hydrates. We observe an increase in hygroscopic growth with decreasing particle size (for particle diameters <150 nm) that is independent of the particle generation method. We vary the hygroscopic growth of the inorganic sea salt within a general circulation model and show that a reduced hygroscopicity leads to a reduction in aerosol-radiation interactions, manifested by a latitudinal-dependent reduction of the aerosol optical depth by up to 15%, while cloud-related parameters are unaffected. We propose that a value of κs=1.1 (at RH=90%) is used to represent the hygroscopicity of inorganic sea salt particles in numerical models.

Measured Saturation Vapor Pressures of Phenolic and Nitro-aromatic Compounds

Bannan, TJ; Booth, AM; Jones, BT; O'Meara, S; Barley, MH; Riipinen, I; Percival, CJ; Topping, D
2017 | Environ. Sci. Technol. | 51 (7) (3922-3928)
aerosol formation , benzoic-acids , dicarboxylic-acids , enthalpies , mass spectrometry , nonelectrolyte organic-compounds , particulate matter , pure component properties , soa formation , solid-state

Phenolic and nitro-aromatic compounds are extremely toxic components of atmospheric aerosol that are currently not well understood. In this Article, solid and subcooled-liquid-state saturation vapor pressures of phenolic and nitro-aromatic compounds are measured using Knudsen Effusion Mass Spectrometry (KEMS) over a range of temperatures (298-318 K). Vapor pressure estimation methods, assessed in this study, do not replicate the observed dependency on the relative positions of functional groups. With a few exceptions, the estimates are biased toward predicting saturation vapor pressures that are too high, by 5-6 orders of magnitude in some cases. Basic partitioning theory comparisons indicate that overestimation of vapor pressures in such cases would cause us to expect these compounds to be present in the gas state, whereas measurements in this study suggest these phenolic and nitro-aromatic will partition into the condensed state for a wide range of ambient conditions if absorptive partitioning plays a dominant role. While these techniques might have both structural and parametric uncertainties, the new data presented here should support studies trying to ascertain the role of nitrogen containing organics on aerosol growth and human health impacts.

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